The invention relates to a gas bag module.
The invention relates in particular to a driver""s or passenger""s gas bag module with a large-volume bag which protects the head and the upper body in a frontal impact.
More particularly, the invention relates to gas bags having a depression and a ring section arranged so as to extend around this depression.
Gas bags having a depression and an annular chamber formed thereby are distinguished by a small stress on the occupant which occurs when the occupant and the gas bag meet. In particular with an occupant who is sitting too close to the steering wheel for example, the unfolding gas bag can hit the occupant and exert stresses on him. In a conventional gas bag, the gas bag bulges out toward the occupant, so that the latter may undergo a reduced restraining effect by the gas bag when the occupant is sitting too close to the steering wheel. In addition, it can not be excluded theoretically that the occupant slides off the gas bag if the occupant is sitting too close to the steering wheel.
A gas bag module may have a heavy emblem of the vehicle manufacturer fastened to the outer side of the cover. In the case of the sudden swinging up of the module covering, it must be ensured that the emblem is held on the covering, which requires an increased expenditure.
The invention faces the object of guaranteeing a simple manufacture of a gas bag module having an annular gas bag, in particular of providing for a reliable fastening of the center section.
This is achieved by a gas bag module which comprises a gas bag with a gas bag wall, the latter including a front wall which faces an occupant to be restrained and which has a center section, and including a rear wall with an inflation opening to connect to a gas generator. The gas bag module also comprises a fastener which holds the center section in a fully inflated state of the gas bag fastened to the module and, upon inflation of the gas bag, prevents the center section from a free movement towards outside of said module, so that a depression is formed by the center section. The gas bag module further comprises a module covering which is opened in a case of restraint for an emergence of the gas bag, the module covering having an annular, predetermined outlet opening which surrounds the fastener. The module covering has a holding section encircled by the outlet opening, and an emblem being provided adjoining the holding section. This emblem is visible from outside, is configured as a separate part and is fastened to the module by the same fastener which fastens the center section to the module. According to the invention, the emblem is fastened to the module to prevent part of the center section from emerging from the module.
In the gas bag module proposed, the fastener which fastens the emblem to the module, has a further function, in that it prevents the center section from an unimpeded movement out of the module, so that a separate fastener for the center section is no longer necessary. In addition, in the gas bag module proposed there is no need for the heavy emblem to fold outwards, so that no danger originates with the emblem, because it is in fact provided on the holding section of the module covering which does not swivel outwards. As a result, the swivelled open flaps on the rest of the module covering does not have to be so stable because the flaps have no heavy emblem and they are a smaller size than in the prior art.
The region of the module covering, which lies inwards of the outlet opening, i.e. is surrounded by it, represents a holding section which forms the fastening of the center section. The holding section therefore has a dual function by on the one hand serving for the restraint of the center section and on the other hand for fastening the flaps to the module covering.
The holding section is preferably fastened to a retainer in the gas bag module, e.g. a cage surrounding the gas generator, which in turn is fastened to the gas generator, to the module housing or for example to a gas generator holding plate, i.e. to a very stable part connected as directly as possible with the vehicle.
The depression with the center section does not have to be a perfectly circular opening, as seen onto the front wall. An embodiment makes provision that in the fully inflated state, viewed onto the front wall, a slit-shaped opening is produced, i.e. a slit-shaped region is formed as transition from the ring section of the front wall to the depression. This means that the depression closes increasingly, starting from the fastener in the region of the covering toward the ring section. This geometry in the fully inflated state of the gas bag can be achieved by a corresponding shape of the gas bag wall in the region of the depression (also designated as the inner gas bag wall) and a corresponding blank of the adjoining, outer gas bag wall or front wall. Furthermore, it is also possible that the depression in the fully inflated state is closed towards the front wall, by the gas bag wall, which delimits the depression, extending radially inwards until opposite sections of the gas bag wall contact each other. In this case, the depression becomes increasingly narrow, starting from the fastener to the ring section, and is finally closed.
The manufacture of the gas bag in the region of the deep depression may possibly be a problem. This depression could for example consist of a piece of fabric sewn to form a tube, the problem then consisting here, however, in fastening this piece of fabric to the remainder of the front wall (ring section). An embodiment of the invention provides for a simple manufacture of the gas bag provided in the gas bag module proposed by the depression being delimited by an inner gas bag wall which consists of at least two wall parts, namely a forward and a rearward wall part. The forward wall part, i.e. the wall part closer to the front side, has an annular blank and is connected by its inner edge with the inner edge of the ring section of the front wall, with the inner edges delimiting an opening for the formation of the center section. The rearward wall part, i.e. the wall part closer to the rear wall, is connected with the outer edge of the forward wall part, preferably with its own outer edge. The fastener which prevents the center section from turning outwards, engages in this embodiment on the rearward wall part. In this development, the gas bag looks like two gas bags fitted into each other, in which the inner gas bag is inserted via the opening on the ring section into the outer gas bag. This embodiment is distinguished on the one hand by a simple manufacture, in particular a simple sewing of the wall parts. On the other hand, it has been found surprisingly that this gas bag offers better restraint values than a gas bag in which the center section is formed by a tube.
To sum up, in the module proposed, the gas bag will remain fastened permanently, in the region of the center section, directly to the module or close to the module, i.e. preferably the module housing. The gas bag is then annular in shape and pushes outwards via an annular flap arrangement.